assume cs:code

code segment
                mov ax,4c00H
                int 21H

    start:      mov ax,0
    s:          nop
                nop

                mov di,OFFSET s
                mov si,OFFSET s2
                mov ax,cs:[si]
                mov cs:[di],ax

    s0:         jmp short s

    s1:         mov ax,0
                int 21H
                mov ax,0

    s2:         jmp short s1
                nop

code ends
end start
